The germination processes of ARS-1590, ARS-1261 and ARS-1229 isolates of Zoophthora radicans (Brefeld) Batko on fifth-instar Empoasca kraemeri (Ross & Moore, 1957) nymphs, at 20ºC and 100% relative humidity were investigated and compared. The primary conidia on the insect germinated within two hours after inoculation for all isolates. The total production of germ tubes tended to be equal to that of capilliconidium on the host body, 12 hours after inoculation. The secondary conidia proportion, among the forms produced by the primary conidia on the insect, did not exceed 25% in all body regions.